1. Field of the Invention
The present invention generally relates to apparatus for sorting objects, and in particular, the present invention relates to an improved sorting apparatus for separating dirt clods, rocks and small debris from root crops such as potatoes.
2. Description of the Prior Art
U.S. Pat. No. 4,081,362 to Chamberlin et al discloses a sorting apparatus for sorting red tomatoes from green or cull tomatoes that includes a solid belt conveyor having a number of longitudinally extending ribs which are uniformly transversely spaced to provide channels for receiving and channelizing tomatoes to be sorted. The tomatoes are ejected from the discharge end of such channelizing conveyor through predetermined trajectories so that the tomatoes fall onto a take-away conveyor which is disposed below and somewhat downstream from the discharge end of the channelizing conveyor. The Chamberlin et al sorting apparatus further includes a number of paddles which are pivotally mounted at positions adjacent the discharge end of the channelizing conveyor, with such paddles being aligned with the lanes of the channelizing conveyor. Each paddle is operated by a solenoid which swings the paddle between an extended position projecting into the trajectory of a tomato from an associated lane of the channelizing conveyor and a retracted position which is cleared from such trajectory. Photodetector units are provided for each lane, and each unit includes a photocell arranged to view the tomato between the respective paddle and the discharge end of the channelizing conveyor. When a green tomato is detected, a solenoid is energized to extend the associated paddle into the trajectory of the green tomato to divert it from its normal trajectory so that it falls onto the take-away conveyor.
While the sorting apparatus of the aforesaid Chamberlin et al patent has been proven to be generally satisfactory for sorting tomatoes, it has a number of disadvantages when employed to separate rocks, dirt clods and loose debris from root crops such as potatoes. The solid belt type of channelizing conveyor disclosed in this patent does not permit the separation of loose debris, such as very small rocks and clods, from the larger potatoes, rocks and clods fed to such belt. Thus, such debris would be flung with the potatoes and the other material toward the photocells and paddle assemblies, thereby contaminating such parts to thereby require more frequent cleaning and maintenance. Also, the belt type of conveyor may stretch substantially after prolonged use, thus requiring appropriate field adjustments.
As illustrated in U.S. Pat. No. 2,896,728 to Pridy, potato harvesters have for many years employed segmented conveyors comprised of an endless series of bars which are spaced in the direction of travel to permit loose debris, small rocks and small dirt clods to fall between the bars while containing to support larger potatoes thereon. Such conveyors, which are known in the art as "potato chain conveyors," include bars having straight portions which extend transversely of the direction of travel of the chain and which have hook portions at their ends that are pivotally engaged upon the ends of the straight portion of the leading adjacent bar (the term "leading" as used herein, signifies the upstream one of each pair of adjacent bars). That is, the hook portions of each bar lead the straight portion thereof as they travel across the upper reach of the potato chain conveyor.
Anderson et al, U.S. Pat. No. 3,679,050 discloses a segmented bar type of conveyor adapted for use in a potato harvester wherein each of the bars has a molding formed thereon. Each molding has a number of upstanding, resilient, finger-like projections uniformly spaced therealong, and the projections of adjacent bars are arranged in a staggered relation with respect to one another. The projections are so transversely spaced in the direction of travel such that the projections of adjacent bars hold the potatoes with their long axes extending transversely of the direction of travel of the conveyor. As in other known prior art potato chain conveyors, such as described hereinbefore in connection with the Pridy et al patent, each conveyor bar has a straight portion and hook portions at the ends of the straight portion, and the hook portions are interconnected with the straight portion of the adjacent leading bar such that the straight portions of the bars trail behind their hook portions. A segmented conveyor that is somewhat similar to that disclosed in the Anderson et al U.S. Pat. No. 3,679,050 patent is shown in French Pat. No. 964,464 published in Aug., 1950. This French patent discloses a segmented chain conveyor including moldings on the chain bars. The moldings include spaced cylindrical abutments, and the abutments are staggered with respect to the abutments on the adjacent bars of the conveyor.
U.S. Pat. No. 3,975,262 to Sherwood discloses a synchronized produce sorting system adapted to sort potatoes which includes a channelizing conveyor comprised of convoluted rollers, photodetectors upstream from the discharge end of the roller conveyor, and air ejectors situated adjacent the discharge end of the roller conveyor. The rollers are mounted to form pockets between successive rollers to channelize the potatoes, rocks and clods in transversely spaced, single files that are aligned with the photodetectors and air ejectors.
U.S. Pat. No. 3,794,161 to Peterson discloses a potato cutting machine which also employs a conveyor comprised of convoluted rollers adapted to channelize potatoes that are fed to the upstream end thereof. As shown in this patent, the rotation of the rollers causes the potatoes to turn and fall lengthwise between the adjacent rollers such that the long axes of the potatoes extend transversely of the direction of travel of the roller conveyor.